Intelligent seawater cooling system

ABSTRACT

A seawater cooling system adapted to mitigate salt crystallization in a seawater cooling loop. The system may include a pump operatively connected to the cooling loop and configured to pump seawater through the cooling loop, a temperature sensor operatively connected to the cooling loop and configured to monitor a temperature of the seawater in the cooling loop, and a controller operatively connected to the temperature sensor and to the pump, the controller configured to issue a warning and to increase a speed of the pump if it is determined that the monitored temperature of the seawater exceeds a predetermined threshold temperature.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is divisional of pending U.S. non-provisional patent applicationSer. No. 15/505,460, filed Feb. 21, 2017, which is a national stageapplication under 35 U.S.C. 371 of International Patent ApplicationPCT/US2015/043355, filed Aug. 3, 2015, which claims priority to U.S.Provisional Patent Application Ser. No. 62/040,089, filed Aug. 21, 2014,the entirety of which applications are incorporated by reference herein.

FIELD OF THE DISCLOSURE

The disclosure is generally related to the field of seawater coolingsystems, and more particularly to a system and method for controllingthe temperature in a fresh water cooling loop by regulating pump speedin a seawater cooling loop thermally coupled thereto.

BACKGROUND OF THE DISCLOSURE

Large seafaring vessels are commonly powered by large internalcombustion engines that require continuous cooling under variousoperating conditions, such as during high speed cruising, low speedoperation when approaching ports, and full speed operation for avoidingbad weather, for example. Existing systems for achieving such coolingtypically include one or more pumps that draw seawater into heatexchangers onboard a vessel. The heat exchangers are used to cool aclosed, fresh water cooling loop that flows through and cools theengine(s) of the vessel and/or other various loads onboard the vessel(e.g., air conditioning systems).

A shortcoming associated with existing seawater cooling systems such asthat described above is that they are generally inefficient.Particularly, the pumps that are employed to draw seawater into suchsystems are typically operated at a constant speed regardless of theamount of seawater necessary to achieve sufficient cooling of theassociated engine. Thus, if an engine does not require a great deal ofcooling, such as when the engine is idling or is operating at lowspeeds, or if the seawater being drawn into a cooling system is verycold, the pumps of the cooling system may provide more water than isnecessary to achieve sufficient cooling. In such cases, the coolingsystem will be configured to divert an amount of the fresh water in thefresh water loop directly to the discharge side of the heat exchangers,where it mixes with the rest of the fresh water that flowed through, andwas cooled by, the heat exchangers. A desired temperature in the freshwater loop is thereby achieved. However, the system does not oftenrequire the full cooling power provided by seawater pumps driven atconstant speed (hence the need to divert water in the fresh water loop).A portion of the energy expended to drive the pumps is therefore wasted.Thus, there is a need for a more efficient seawater pumping system foruse in heat exchange systems servicing the marine industry.

SUMMARY

A seawater cooling system is disclosed for mitigating saltcrystallization in a seawater cooling loop. The system can include apump operatively connected to the cooling loop and configured to pumpseawater through the cooling loop. A temperature sensor can beoperatively connected to the cooling loop and configured to monitor atemperature of the seawater in the cooling loop. A controller can beoperatively connected to the temperature sensor and to the pump. Thecontroller can be configured to increase a speed of the pump when thecontroller determines, from a signal received from the temperaturesensor, that a monitored temperature of the seawater exceeds apredetermined threshold temperature.

A method is disclosed for mitigating salt crystallization in a seawatercooling loop. The method can include: measuring a temperature ofseawater in the cooling loop; comparing the measured temperature of theseawater to a predetermined threshold temperature; and increasing aspeed of a pump circulating the seawater through the cooling loop whenthe measured temperature of the seawater exceeds the predeterminedthreshold temperature.

A seawater cooling system is disclosed for monitoring and reducingclogging in a seawater cooling loop. The system can include a pressuresensor operatively connected to the cooling loop and configured tomeasure a fluid pressure of seawater in the cooling loop. A plurality ofvalves may be connected to the cooling loop and configured toselectively change a flow direction of the seawater through the coolingloop between a first direction, during normal operation, and seconddirection opposite the first direction, during a back flushingoperation. A controller can be operatively connected to the pressuresensor and to the plurality of valves, the controller configured tooperate the plurality of valves to change flow from the first directionto the second direction when the pressure of the seawater exceeds apressure level associated with a predetermined maximum clogging level.

A method for monitoring and reducing clogging in a seawater cooling loopis disclosed. The method can comprise: circulating seawater through thecooling loop using a pump operating at a predetermined speed; measuringa pressure of the seawater while the pump is operated at thepredetermined speed; comparing the measured pressure to a predeterminedpressure, the predetermined pressure associated with a baselinecondition of the cooling loop; and reversing the circulation directionof the seawater through the cooling loop when the measured pressureexceeds the predetermined pressure by a predetermined amount.

An overlapping pump system is disclosed. The system can comprise firstand second pumps coupled to a seawater cooling loop for circulatingseawater through the seawater cooling loop, and first and secondcontrollers operatively coupled to the first and second pumps,respectively. The first and second controllers may be configured toperform a handshake operation for switching operation between the firstand second pumps. The handshake operation may include: sending, from thefirst controller to the second controller, a request for the secondcontroller to start operation of the second pump, upon receipt of therequest, sending, from the second controller, an acknowledgement to thefirst controller when the second pump is capable of starting operation,and upon receiving, at the first controller, the acknowledgement, thefirst controller shutting down the first pump.

A method for overlapping operation of a first pump and a second pump isdisclosed. The method may comprise: sending, from a first controllercoupled to the first pump, a request to a second controller coupled tothe second pump, a request for the second controller to start operationof the second pump; upon receipt of the request, sending, from thesecond controller, an acknowledgement to the first controller when thesecond pump is capable of starting operation; and upon receiving, at thefirst controller, the acknowledgement, shutting down the first pump.

BRIEF DESCRIPTION OF THE DRAWINGS

By way of example, specific embodiments of the disclosed device will nowbe described, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic view illustrating an exemplary intelligentseawater cooling system in accordance system.

FIG. 2 is a flow diagram illustrating an exemplary method for operatingthe intelligent seawater cooling system shown in FIG. 1 in accordancewith the present disclosure.

FIG. 3 is a flow diagram illustrating an exemplary method forestablishing parameters in the intelligent seawater cooling system shownin FIG. 1 in accordance with the present disclosure.

FIG. 4 is a flow diagram illustrating an exemplary method for equalizingpump usage in the intelligent seawater cooling system shown in FIG. 1 inaccordance with the present disclosure.

FIG. 5 is a graph illustrating energy savings as a result of reductionsin pump speeds.

FIG. 6 is a graph illustrating exemplary means for determining whetherto operate the system of the present disclosure with 1 pump or 2 pumps.

FIG. 7 is a flow diagram illustrating an exemplary method for mitigatingsalt crystallization in a seawater cooling loop of the intelligentseawater cooling system shown in FIG. 1 in accordance with the presentdisclosure.

FIG. 8 is a flow diagram illustrating an exemplary method for monitoringand reducing clogging in a seawater cooling loop of the intelligentseawater cooling system shown in FIG. 1 in accordance with the presentdisclosure.

FIG. 9 is a flow diagram illustrating an exemplary method foroverlapping the operation of a first pump and a second pump in theintelligent seawater cooling system shown in FIG. 1 in accordance withthe present disclosure.

DETAILED DESCRIPTION

An intelligent seawater cooling system and method in accordance with thepresent disclosure will now be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the system and method are shown. The disclosed system and method,however, may be embodied in many different forms and should not beconstrued as limited to the embodiments set forth herein. Rather, theseembodiments are provided so that this disclosure will be thorough andcomplete, and will fully convey the scope of the invention to thoseskilled in the art. In the drawings, like numbers refer to like elementsthroughout.

Referring to FIG. 1, a schematic representation of an exemplaryintelligent seawater cooling system 10 (hereinafter “the system 10”) isshown. The system 10 may be installed onboard any type of seafaringvessel or offshore platform having one or more engines 11 that requirecooling. Only a single engine 11 is shown in FIG. 1, but it will beappreciated by those of ordinary skill in the art the engine 11 may berepresentative of a plurality of engines or various other loads onboarda vessel or platform that may be coupled to the cooling system 10.

The system 10 may include a seawater cooling loop 12 and a fresh watercooling loop 14 that are thermally coupled to one another by a heatexchanger 15 as further described below. Only a single heat exchanger 15is shown in FIG. 1, but it is contemplated that the system 10 mayalternatively include two or more heat exchangers for providing greaterthermal transfer between the seawater cooling loop 12 and the freshwater cooling loop 14 without departing from the present disclosure.

The seawater cooling loop 12 of the system 10 may include a main pump16, a secondary pump 18, and a backup pump 20. The pumps 16-20 may bedriven by respective variable frequency drives 22, 24, and 26(hereinafter “VFDs 22, 24, and 26”). The pumps 16-20 may be centrifugalpumps, but it is contemplated that the system 10 may alternatively oradditionally include various other types of pumps, including, but notlimited to, gear pumps, progressing cavity pumps, or multi-spindle screwpumps, or other positive-displacement pumps or other non-positivedisplacement pumps.

The VFDs 22-26 may be operatively connected to respective main,secondary, and backup controllers 28, 30, and 32 via communicationslinks 40, 42, and 44. Various sensors and monitoring devices 35, 37, and39, including, but not limited to, vibration sensors, pressure sensors,bearing temperature sensors, leakage sensors, and other possiblesensors, may be operatively mounted to the pumps 16, 18 and 20 andconnected to the corresponding controllers 28, 30 and 32 via thecommunications links 34, 36, and 38. These sensors may be provided formonitoring the health of the pumps 16, 18, and 20 as further describedbelow.

The controllers 28-32 may further be connected to one another bycommunications link 46. The communications link 46 may be transparent toother networks, providing supervising communication capability. Thecontrollers 28-32 may be configured to control the operation of the VFDs22-26 (and therefore the operation of the pumps 16-20) to regulate theflow of seawater to the heat exchanger 15 as further described below.The controllers 28-32 may be any suitable types of controllers,including, but not limited to, proportional-integral-derivative (PID)controllers and/or a programmable logic controllers (PLCs). Thecontrollers 28-32 may include respective memory units and processors(not shown) that may be configured to receive and store data provided byvarious sensors in the cooling system 10, to communicate data betweencontrollers and networks outside of the system 10, and to store andexecute software instructions for performing the method steps of thepresent disclosure as described below.

An operator may establish a plurality of pump parameters at thecontroller 28, VFD 22, or other user interface. Such pump parameters mayinclude, but are not limited to, a reference speed, a referenceefficiency, a reference flow, a reference head, a reference pressure,speed limits, suction pressure limits, discharge pressure limits,bearing temperature limits, and vibration limits. These parameters maybe provided by a pump manufacturer (such as in a reference manual) andmay be entered into the controller 28, VFD 22, or other user interfaceby the operator or by external supervising devices via thecommunications link 46. Alternatively, it is contemplated that thecontroller 28, VFD 22, or other user interface may be preprogrammed withpump parameters for a plurality of different types of commerciallyavailable pumps, and that the operator may simply specify the type ofpumps that are currently being used by the system 10 to load acorresponding set of parameters. It is further contemplated that thecontroller 28 or VFD 22 may be configured to automatically determine thetype of pumps that are connected in the system 10 and to load acorresponding set of parameters without any operator input.

An operator may also establish a plurality of system parameters at thecontroller 28, VFD 22, or other user interface. Such parameters mayinclude, but are not limited to, a fresh water temperature range, a VFDmotor speed range, a minimum pressure level, a fresh water flow, a waterheat capacity coefficient, a heat exchanger surface area, a heattransfer coefficient, presence of a 3-way valve, and ambient temperaturelimits.

Pump parameters and system parameters that are established at thecontroller 28 or VFD 22 may be copied to the other controllers 30 and 32and/or to the other VFDs 24 and 26, such as via transmission ofcorresponding data through the communications link 46. Such copying ofthe parameters may be performed automatically or upon entry of anappropriate command by the operator at the controller 28, VFD 22, orother user interface. The operator is therefore only required to enterthe parameters once at a single interface instead of having to enter theparameters at each controller 28-32 and/or VFD 22-26 as in other pumpsystems.

The communications links 34-46, as well as communications links 81, 104and 108 described below, are illustrated as being hard wiredconnections. It will be appreciated, however, that the communicationslinks 34-46, 91, 104 and 108 of the system 10 may be embodied by any ofa variety of wireless or hard-wired connections. For example, thecommunications links 34-46, 91, 104 and 108 may be implemented usingWi-Fi, Bluetooth, PSTN (Public Switched Telephone Network), a satellitenetwork system, a cellular network such as, for example, a GSM (GlobalSystem for Mobile Communications) network for SMS and packet voicecommunication, General Packet Radio Service (GPRS) network for packetdata and voice communication, or a wired data network such as, forexample, Ethernet/Internet for TCP/IP, VOIP communication, etc.

The seawater cooling loop 12 may include various piping and pipingsystem components (“piping”) 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 69,70, 109, 110, 111, 112, 113, 114 for drawing water from the sea 72,through the pumps 16-20, and for circulating the seawater through theseawater cooling loop 12, including a seawater side of the heatexchanger 15, as further described below. The piping 50-70 and 109-114,as well as piping 84, 86, 88, 90, 92, 94, 95, 97, 99 and 101 of thefresh water cooling loop 14 and the additional systems 103, 105, and 107described below, may be any type of rigid or flexible conduits, pipes,tubes, or ducts that are suitable for conveying seawater, and may bearranged in any suitable configuration aboard a vessel or platform asmay be appropriate for a particular application.

The seawater cooling loop 12 may further include a discharge valve 89disposed intermediate the conduits 69 and 70 and connected to the maincontroller 28 via communications link 91. It is contemplated that thedischarge valve 89 may also be connected to the secondary controller 30and/or the backup controller 32, as these controllers may automaticallyidentify the connected discharge valve 89 and may automaticallydistribute information pertaining to the connection of the dischargevalve 89 to one another via the communications link 46. The dischargevalve 89 may be adjustably opened and closed to vary the operationalcharacteristics (e.g., pressure) of the pumps 16-20 as further describedbelow. In one non-limiting exemplary embodiment, the discharge valve 89is a throttle valve.

The seawater cooling loop 12 may further include flow regulation valves115, 116, 117, 118 disposed intermediate conduits 66 and 109, 110 and68, 111 and 112, and 113 and 114, respectively. The flow regulationvalves 115-118 may be connected to the main controller 28 viacommunications link 91 (as shown in FIG. 1) and/or via one or moreadditional communications links for controlling operation of thosevalves. It is contemplated that the flow regulation valves 115-118 mayalso be connected to the secondary controller 30 and/or the backupcontroller 32, as these controllers may automatically identify theconnected discharge valve 89 and may automatically distributeinformation pertaining to the connection of the discharge valve 89 toone another via the communications link 46. The flow regulation valves115-118 may be selectively opened and closed to vary the direction inwhich seawater is circulated through heat exchanger 15. Particularly,during normal operation of the system 10, the flow regulation valves115, 116 may be open and the flow regulation valves 117, 118 may beclosed to circulate seawater through the heat exchanger 15 in a firstdirection for cooling the fresh water in the fresh water cooling loop 14as further described below.

As will be appreciated it can be desirable to periodically backflush theheat exchanger 15 to remove organic matter and/or other buildup that canaccumulate in the tubes and/or between the plates during extendedoperation. Thus, as will be described, the disclosed system can beemployed to automatically and/or manually configure itself into a backflushing mode. During a back flushing operation, the flow regulationvalves 115, 116 may be closed and the flow regulation valves 117, 118may be opened to circulate seawater through the heat exchanger 15 in asecond direction opposite the first direction, thereby back-flushing andcleaning the heat exchanger 15 will be further described below inrelation to FIG. 8.

The seawater cooling loop 12 may further include a resistancetemperature detector 119 (hereinafter “RTD 119”) or other temperaturemeasurement device that is operatively connected to a discharge side ofthe heat exchanger 15, such as at a position upstream of the dischargevalve 89 intermediate the conduits 68 and 69. The RTD 119 may beconnected to the main controller 28 via communications link 91 and/orvia one or more additional communications links. It is contemplated thatthe RTD 119 may also be connected to the secondary controller 30 and/orthe backup controller 32, as these controllers may automaticallyidentify the connected RTD 119 and may automatically distributeinformation pertaining to the connection of the RTD 119 to one anothervia the communications link 46. The RTD 119 may be used to monitor atemperature of the seawater in the seawater cooling loop 12, such as fordetermining whether the seawater is approaching a temperature at whichsalt in the seawater may crystalize. If it is determined that theseawater is approaching such a temperature, the main controller 28 mayoperate one or more of the pumps 16-20 to mitigate salt crystallizationas further will be described below in relation to FIG. 7.

The fresh water cooling loop 14 of the system 10 may be a closed fluidloop that includes a fluid pump 80 and various piping and components 84,86, 88, 90, 92, and 94 for continuously pumping and conveying freshwater through the heat exchanger 15 and the engine 11 for cooling theengine 11 as further described below. The fresh water cooling loop 14may further include a 3-way valve 102 that is connected to the maincontroller 28 via communications link 104 for controllably allowing aspecified quantity of water in the fresh water cooling loop 14 to bypassthe heat exchanger 15 as further described below.

A temperature in the fresh water cooling loop 14 may be measured andmonitored by the main controller 28 to facilitate various controloperations of the cooling system 10. Such temperature measurement may beperformed by a resistance temperature detector 106 (hereinafter “RTD106”) or other temperature measurement device that is operativelyconnected to the fresh water cooling loop 14. The RTD 106 is shown inFIG. 1 as measuring the temperature of the fresh water cooling loop 14on the inlet side of the engine 11, but it is contemplated that the RTD106 may alternatively or additionally measure the temperature of thefresh water cooling loop 14 on the outlet side of the engine 11. The RTD106 may be connected to the main controller 28 by communications link108 or, alternatively, may be an integral, onboard component of the maincontroller 28. It is contemplated that the RTD 106 may also be connectedto the secondary controller 30 and/or the backup controller 32, as thesecontrollers may automatically identify the connected RTD 106 and mayautomatically distribute information pertaining to the connection of theRTD 106 to one another via the communications link 46.

The seawater cooling loop 12 may additionally provide seawater tovarious other systems of a vessel or platform for facilitating theoperation of such systems. For example, seawater from the seawatercooling loop 12 may be provided to one or more of a fire suppressionsystem 103, a ballast control system 105, and/or a seawater steeringsystem 107 on an as-needed basis. Although not shown, otherseawater-operated systems that may receive seawater from the seawatercooling loop 12 in a similar manner include, but are not limited to,sewage blowdown, deck washing, air conditioning, and fresh watergeneration.

In the exemplary system 10 shown in FIG. 1, seawater may be provided tothe systems 103-107 via piping 95, 97, 99, and 101, which may beconnected to the seawater cooling loop 12 at piping 66, for example. Thepiping 95-101 may be provided with various manually or automaticallycontrolled valves (not shown) for directing the flow of seawater intothe systems 103-107 in a desired manner. Of course, it will beappreciated that if seawater is supplied to the systems 103-107, theflow of seawater through the heat exchanger 15 will be reduced, whichmay cause the temperature in the fresh water cooling loop 14 to riseunless the operation of the pumps 16-20 is modified. The pumps 16-20 maytherefore be controlled in manner that compensates for the use ofseawater by the systems 103-107 as will described in greater detailbelow.

It is contemplated that the system 10 may monitor the total amount oftime that each of the pumps 16-20 has been operating and may reallocatethe operation of the pumps 16-20 in a manner that equalizes, or attemptsto equalize, the operating times of the pumps 16-20. For example, if themain pump 16 has logged 100 hours of operation, the secondary pump 18has logged 50 hours of operation, and the backup pump has logged only 5hours of operation, the system 10 may reassign the primary pump 16 tooperate as a backup pump and may reassign the backup pump 20 to operateas a primary pump. The pumps 18 and 20 may thereby continue toaccumulate significant operating time while the pump 16 remainssubstantially idle. By equalizing the operating times of the pumps 16-20thusly, the pumps 16-20 may be caused to wear at a substantially uniformrate and may therefore be serviced or replaced according to a uniformschedule.

The above-described equalization procedure may be performedautomatically, such as accordingly to a predefined schedule. Forexample, when one of the pumps 16-20 accumulates a predefined (e.g.,operator-defined) amount of operating time since a last reallocation,the equalization procedure may be performed and the roles of the pumps16-20 may be reassigned as necessary to equalize usage. The equalizationprocedure may also be initiated manually at the discretion of anoperator, such as through the entry of an appropriate command at anoperator interface.

The system 10 may be operated in a variety of differentoperator-selectable modes, such as may be selected via an operatorinterface (not shown), wherein each operating mode may dictate aparticular minimum system pressure that will be maintained by the system10. For example, a first operating mode may be a “no threshold” orsimilarly designated mode which, if selected, will cause the system 10to operate the pumps 16-20 without regard to any predetermined orspecified minimum system pressure. That is, the system 10 will operatethe pumps 16-20 based solely on the cooling demands of the engine 11.For example, if seawater is taken from the seawater cooling loop 12 byany of the seawater-operated systems (e.g., the ballast control system105), the flow of seawater through the heat exchanger 15 will decrease,thereby reducing the amount of cooling in the fresh water cooling loop14. The temperature of the water in the fresh water cooling loop 14 maytherefore increase. As described above, the main controller 28 may thendetermine that the monitored temperature of the fresh water exceeds, oris about to exceed, a predefined temperature level, and the maincontroller 28 may respond by increasing the speed of the VFD 22 and mayissue a command to the secondary controller 30 to increase the speed ofthe VFD 24 to the speed of the VFD 22, for example. The correspondingmain and/or secondary pumps 16 and 18 are thereby driven faster, and theflow of seawater through the seawater cooling loop 12 is increased.Greater cooling is thereby provided at the heat exchanger 15, and thetemperature in the fresh water cooling loop 14 is resultantly decreased.Thus, a sufficient amount of seawater may be supplied for cooling theengine 11 and for operating a ship's seawater-operated systems in apurely “on-demand” fashion by driving the pumps 16-20 only as necessaryto meet contemporaneous needs, thereby optimizing the efficiency of thesystem 10. This is to be contrasted with conventional seawater coolingsystems, in which a minimum system pressure (i.e., a minimum seawaterpressure that has been determined to be necessary for operating some orall of a ship's seawater-operated systems) is constantly maintainedregardless of contemporaneous system needs.

A second selectable operating mode may be a “minimum threshold” orsimilarly designated mode which, if selected, may allow an operator tomanually enter a minimum threshold value and will thereafter cause thesystem 10 to operate the pumps 16-20 in a manner that will keep a ship'ssystem pressure above the manually specified threshold value. Theminimum threshold value may be a value that is below a minimum systempressure (described above), but that provides some constantly maintainedamount of seawater pressure in a ship's system. The ship's systempressure may be monitored by sensors that are integral with the ship andthat are independent of the system 10, and may be communicated to thesystem 10 via a communications link, such as the communications link 46.The “minimum threshold” mode may be suitable for situations in which asystem operator is not comfortable with operating the system 10 in apurely on-demand manner (as in the “no threshold” mode described above)but still wants to achieve a greater level of system efficiency relativeto traditional seawater cooling systems in which a minimum systempressure in constantly maintained. After a system operator becomescomfortable with the on-demand capability of the system 10, the operatormay lower or completely remove the minimum threshold value. Thisflexibility provides system operators with options to fit theirapplication needs.

A third selectable operating mode may be a “minimum system pressure” orsimilarly designated mode which, if selected, will cause the system 10to operate the pumps 16-20 in manner that will keep a ship's systempressure above the ship's predetermined (e.g., pre-calculated) minimumsystem pressure. As described above, the minimum system pressure may bea minimum seawater pressure that has been determined to be necessary foroperating some or all of a ship's seawater-operated systems. Again, aship's system pressure may be monitored by sensors that are integralwith the ship and that are independent of the system 10, and may becommunicated to the system 10 via a communications link. The “minimumsystem pressure” mode may be suitable for situations in which a systemoperator is not comfortable with operating the system 10 in a purelyon-demand manner (as in the “no threshold” mode described above) or withmaintaining a system pressure that is less than the minimum systempressure (as in the “minimum threshold” mode described above).

It will be appreciated that the above-described operating modes providethe system 10 with the flexibility to suit the preferences of varioussystem operators without requiring any reconfiguration of systemcomponents prior to installation. Additionally, if the preferences of anoperator change over time, such as if an operator is initially hesitantto operate the system 10 at less than a minimum system pressure, theoperator may seamlessly switch between operating modes and graduate topurely on-demand operation as his/her comfort level increases.

Referring to FIG. 2, a flow diagram illustrating a general exemplarymethod for operating the system 10 in accordance with the presentdisclosure is shown. The method will be described in conjunction withthe schematic representation of the system 10 shown in FIG. 1. Unlessotherwise specified, the described method may be performed wholly or inpart by the controllers 28-32, such as through the execution of varioussoftware algorithms by the processors thereof.

At step 200, the system 10 may be activated, such as by an operatormaking an appropriate selection in an operator interface (not shown) ofthe system 10. Upon such activation, the operator may be prompted toselect an operating mode which may dictate a minimum system pressurethat will be maintained by the system 10. For example, the operator maybe prompted to select one of the described above “no threshold,”“minimum threshold,” or “minimum system pressure” operating modes.

Once the system 10 has been activated and an operating mode has beenspecified, the main and secondary controllers 28 and 30 may, at step 210of the exemplary method, command the VFDs 22 and 24 to begin driving atleast one of the pumps 16 and 18. The pumps 16 and 18 may thus beginpumping seawater from the sea 72, through the piping 52 and 54, throughthe pumps 16 and 18, through the piping 58-66, through the heatexchanger 15, and finally through the piping 68 and 70 and back to thesea 72. As the seawater flows through the heat exchanger 15, it may coolthe fresh water in the fresh water cooling loop 14 that also flowsthrough the heat exchanger 15. The cooled fresh water thereafter flowsthrough and cools the engine 11.

At step 220 of the exemplary method, the main controller 28 may monitorthe temperature of the fresh water in the fresh water cooling loop 14via the RTD 106. The main controller 28 may thereby determine whetherthe fresh water is at a desired temperature for providing the engine 11with appropriate cooling, such as by comparing the monitored temperatureto a predefined temperature level and a predefined temperature range.For example, the desired temperature level of the fresh water at thedischarge of the heat exchanger may be 35 degrees Celsius, and thepredefined temperature range may be +/−3 degrees Celsius.

If the main controller 28 determines at step 220 that the monitoredtemperature of the fresh water exceeds, or is about to exceed, apredefined temperature level, the main controller 28 may, at step 230 ofthe exemplary method, increase the speed of the VFD 22 and may issue acommand to the secondary controller 30 to increase the speed of the VFD24 to the speed of the VFD 22, for example. The corresponding mainand/or secondary pumps 16 and 18 are thereby driven faster, and the flowof seawater through the seawater cooling loop 12 is increased. Greatercooling is thereby provided at the heat exchanger 15, and thetemperature in the fresh water cooling loop 14 is resultantly decreased.

Conversely, if the main controller 28 determines at step 220 that themonitored temperature of the fresh water is below, or is about to fallbelow, a predefined temperature level, the main controller 28 may, atstep 240 of the exemplary method, decrease the speed of the VFD 22 andmay issue a command to the secondary controller 30 to decrease the speedof the VFD 24 to the speed of the VFD 22, for example. The correspondingmain and secondary pumps 16 and 18 are thereby driven more slowly, andthe flow of seawater through the seawater cooling loop 12 is decreased.Less cooling is thereby provided at the heat exchanger 15 and thetemperature in the fresh water cooling loop 14 is resultantly increased.Under certain circumstances, such as if the fresh water temperature isstill too low (e.g., below the desired temperature level or below thelower value of the predefined temperature range) and the pump speedscannot be lowered further due to the requirement of maintaining minimumsystem pressure and/or minimum pump speed, the main controller 28 mayadditionally command the 3-way valve 102 to adjust its position, therebydiverting some or all of the fresh water in the fresh water cooling loop14 to bypass the heat exchanger 15 in order to further reduce thecooling of the fresh water.

Regardless of how little cooling the engine 11 may require, if the“minimum threshold” mode or the “minimum system pressure” mode wereselected in step 200 above, the pumps 16 and 18 will not be driven atspeeds that would allow the monitored ship's system pressure to fallbelow the predetermined minimum system pressure or the specified minimumthreshold value (described above), respectively. Some minimum level ofseawater pressure may therefore be maintained in the ship's system atall times for supplying seawater to the seawater-operated systems.

If the “no threshold” mode was selected in step 200, the system 10 willnot operate according to any predetermined or specified minimum systempressure, but will instead operate solely in response to the coolingrequirements of the engine 11 as described above to ensure that asufficient amount of seawater is pumped in an on-demand manner toprovide engine cooling and to supply seawater-operated systems.

Under certain circumstances, such as if the system 10 is operating inparticularly cold waters and/or if the engine 11 is idling, it may bedesirable to reduce the flow of seawater in the seawater cooling loop 12to a rate below what may be achieved through the reduction of the pumpspeeds while maintaining stable operation of the pumps 16 and 18. Thatis, regardless of how little flow is required in the seawater coolingloop 12, it may be necessary to run the pumps 16 and 18 at a minimumsafe operating speed to avoid cavitation or damage to the pumps 16 and18, for example. If the main controller 28 determines that such a lowflow rate of seawater is desirable, the main controller 28 may, at step250, decrease the speed of the VFD 22 to drive the main pump 16 at ornear a minimum safe operating speed, may command the secondarycontroller to decrease the speed of the VFD 24 to drive the secondarypump 18 at or near a minimum safe operating speed (or to shut down), andmay further command the discharge valve 89 to partially close in orderto maintain a required minimum system discharging pressure. By partiallyclosing the discharge valve 89 thusly, the flow rate in the seawatercooling loop 12 may be restricted/reduced without further reducing theoperational speeds of the pumps 16 and 18, and the minimum requiredsystem pressure can be maintained. The pumps 16 and 18 may thereby beoperated above their minimum safe operating speeds while achieving adesired low flow rate in the seawater cooling loop 12. The dischargevalve 89 may be controlled in a similar manner for keeping a ship'ssystem pressure above a predetermined or specified system pressure(i.e., if the “minimum system pressure” mode or the “specified pressure”mode were selected in step 200).

By continuously monitoring the temperature in the fresh water coolingloop 14 and adjusting the pump speeds and flow rate in the seawatercooling loop 12 in the manner described above, the pumps 16 and 18 maybe driven only as fast as is necessary to provide a requisite amount ofcooling at the heat exchanger 15 and/or to maintain a predetermined orspecified minimum system pressure. The system 10 may therefore beoperated much more efficiently and may provide significant fuel savingsrelative to traditional seawater cooling systems in which seawater pumpsare driven at a constant speed regardless of temperature variations.Such improved efficiency is illustrated in the graph shown in FIG. 5. Aswill be appreciated by those of ordinary skill in the art, pump power“P” is proportional to the cube of pump speed “n,” while flowrate “Q” isproportional to pump speed “n.” Thus, when the disclosed system 10 isoperated at a lower Q because of lower cooling demand from the engine,in lieu of running the pumps at maximum speed and simply shunting excessflow overboard or through a recirculation loop, substantial powersavings can be achieved. For example, if Q=50% of the rated seawaterflow Qopt, then the pumps 16, 18 need only be operated at 50% of theirrated speed to provide 50% of Qopt. This reduction in speed results in apower “P” reduction of 87.5%, as compared to prior systems in which thepumps 16, 18 are operated at a constant maximum speed (or rated speed).

At step 260 of the exemplary method, the main controller 28 maydetermine whether the system 10 should be operated in a 1-pump mode or a2-pump mode in order to achieve a desired efficiency and more energysavings. That is, it may be more efficient in some situations (e.g., ifminimal cooling is required) to drive only one of the pumps 16 or 18 andnot the other. Alternatively, it may be more efficient and/or necessaryto drive both of the pumps 16 and 18 at a low speed. The main controller28 may make such a determination by comparing the operating speeds ofthe pumps 16 and 18 to predefined “switch points.” “Switch points” isdetermined by the ratio of Q/Qopt of either 1-pump or 2-pump operation,which can yield more efficient system. For example, if the system 10 isoperating in 2-pump mode and both of the pumps 16 and 18 are beingdriven at less than a predetermined efficiency point, the maincontroller 28 may deactivate the secondary pump 18 and run only the mainpump 16. While 1-pump is running, the efficiency Q/Qopt will increase,resulting a more efficient system over 2-pump operation. Conversely, ifthe system 10 is operating in 1-pump operation mode (e.g., running onlythe main pump 16) and the main pump 16 is being driven at greater than apredetermined efficiency point, the main controller 28 may activate thesecondary pump 18.

As shown in FIG. 6, The switch points (between one and two pumpoperation) may be determined based on the actual flow rate “Q” in thesystem 10 compared to optimal flow range “Qopt.” According to theexemplary curve, when Q/Qopt exceeds 127% under single pump operation,the system can switch to two pump operation to operate most efficiently.Likewise, when Q/Qopt falls below 74% under two pump operation, thesystem can switch to single pump operation. At the same time, thedischarging valve is controlled so that the required minimum systemdischarging pressure is maintained at all times.

At step 270 of the exemplary method, the main, secondary, and backupcontrollers 28, 30, and 32 may periodically transmit data packets to oneanother, such as via communications link 46. Such data packets mayinclude information relating to the critical operational status, or“health,” of each of the controllers 28-32 including their respectivepumps 16-20 and VFDs 22-26. If it is determined that one of thecontrollers 28-32 or its respective pump has ceased to operate properly,or is trending in a direction that would indicate a near or far termmalfunction, or if its communications link has malfunctioned or isotherwise inactive, the duties of that controller may be reassigned toanother one of the controllers. For example, if it is determined thatthe secondary controller 30 has ceased to operate properly, the dutiesof the secondary controller 30 may be reassigned to the backupcontroller 32. Alternatively, if it is determined that the maincontroller 28 has ceased to operate properly, the duties of the maincontroller 28 may be reassigned to the secondary controller 30 and theduties of the secondary controller 30 may be subsequently reassigned tothe backup controller 32. The system 10 is thereby provided with a levelof automatic redundancy that allows to the system 10 carry on withnormal operation even after the occurrence of component failures. If theceased or questionable controller is repaired and/or restored tooperational conditions, and is brought back to the operation, theinformation will be broadcast over the communication link to othercontrollers, the backup controller will automatically stop its operationof its pump, and will be in stand-by mode for providing future needs forits backup role.

Referring to FIG. 3, a flow diagram illustrating an exemplary method forinputting operating parameters into the system 10 in accordance with thepresent disclosure is shown.

At a first step 300 of the exemplary method, an operator may establish aplurality of pump parameters at the controller 28, VFD 22, or other userinterface. As described above, such pump parameters may include, but arenot limited to, a reference speed, a reference efficiency, a referenceflow, a reference head, a reference pressure, speed limits, suctionpressure limits, discharge pressure limits, bearing temperature limits,and vibration limits. These parameters may be provided by a pumpmanufacturer (such as in a reference manual) and may, at step 310 a, bemanually entered into the controller 28, VFD 22, or other user interfaceby the operator or by external supervising devices via thecommunications link 46. Alternatively, it is contemplated that thecontroller 28, VFD 22, or other user interface may be preprogrammed withpump parameters for a plurality of different types of commerciallyavailable pumps as described above, and that the operator may, at step310 b, simply specify the type of pumps that are currently being used bythe system 10 to load a corresponding set of parameters. In anothercontemplated embodiment, the controller 28 or VFD 22 may be configuredto automatically determine the type of pumps that are connected in thesystem 10 and to automatically load a corresponding set of parameterswithout any operator input as indicated at step 310 c.

At step 320 of the exemplary method, the operator may establish aplurality of system parameters at the controller 28, VFD 22, or otheruser interface. Such parameters may include, but are not limited to, afresh water temperature range, a VFD motor speed range, a minimumpressure level, a fresh water flow, a water heat capacity coefficient, aheat exchanger surface area, a heat transfer coefficient, presence of a3-way valve, and ambient temperature limits.

At step 330 of the exemplary method, the pump parameters and systemparameters that were established in the preceding steps may be copied tothe other controllers 30 and 32 and/or to the other VFDs 24 and 26, suchas via transmission of corresponding data through the communicationslink 46. Such copying of the parameters may be performed automaticallyor upon entry of an appropriate command by the operator at thecontroller 28, VFD 22, or other user interface. The operator istherefore only required to enter the parameters once at a singleinterface instead of having to enter the parameters at each controller28-32 and/or VFD 22-26 as in other pump systems.

Referring to FIG. 4, a flow diagram illustrating an exemplary method forequalizing usage of the pumps 16-20 of the system 10 in accordance withthe present disclosure is shown.

At step 400 of the exemplary method, the system 10 may monitor the totalamount of time that each of the pumps 16-20 has been operating. At step410, the system 10 may determine whether one of the pumps 16-20 has beenoperating for a specified amount of time longer than at least one of theother pumps 16-20. At step 420, the system 10 may reallocate theoperation of the pumps 16-20 in a manner that equalizes, or attempts toequalize, the operating times of the pumps 16-20. For example, if themain pump 16 has logged 100 hours of operation, the secondary pump 18has logged 50 hours of operation, and the backup pump has logged only 5hours of operation, the system 10 may reassign the primary pump 16 tooperate as a backup pump and may reassign the backup pump 20 to operateas a primary pump. The pumps 16 and 20 may thereby continue toaccumulate significant operating time while the pump 16 remainssubstantially idle. By equalizing the operating times of the pumps 16-20thusly, the pumps 16-20 may be caused to wear at a substantially uniformrate and may therefore be serviced or replaced according to a uniformschedule.

The above-described equalization procedure may be performedautomatically, such as accordingly to a predefined schedule. Forexample, when one of the pumps 16-20 accumulates a predefined (e.g.,operator-defined) amount of operating time since a last reallocation,the equalization procedure may be performed and the roles of the pumps16-20 may be reassigned as necessary to equalize usage. The equalizationprocedure may also be initiated manually at the discretion of anoperator, such as through the entry of an appropriate command at anoperator interface.

Referring now to FIG. 7, a method will be described for mitigating theformation of salt crystals within the cooling system. As will beappreciated, when seawater temperatures within the heat exchanger 15exceed a threshold temperature, salt can crystallize within the coolingsystem. Substantial accumulation of such salt crystals, as can occurover time, can result in undesirable clogging of the heat exchanger, aswell as the system piping and components.

In general, a temperature sensor (such as RTD 119, see FIG. 1) can bemounted at the seawater discharge of the heat exchanger 15 to enableseawater temperature to be monitored by one of the networked controllers28, 30, 32. In some embodiments this information can be shared among thecontrollers in the network. An alarm setpoint can be provided by asystem operator, such that if seawater temperature rises by a prescribedamount (e.g., 5 degrees Celsius) below the alarm setpoint, a warningwill be issued and all operating pumps 16, 18, 20 in the system willoperate at rated speed, to reduce the seawater temperature to preventsalt crystallization. In some embodiments this feature will override thenormal fresh water temperature regulation scheme.

If seawater temperature rises above the alarm setpoint, an alarm willalso be issued. Once the system enters into this “seawater temperaturereduction mode,” and the seawater temperature thereafter drops below thewarning level (e.g., 5 degrees C. below the alarm setpoint), the systemwill go back to the “normal” operation in which fresh water temperatureregulation and minimum system pressure regulation determine theoperational speed of the pumps 16, 18, 20.

The described “seawater temperature reduction mode” facilitatesautomatic prevention of sea salt crystallization and accumulation in thecooling system components. It enables a single temperature input to bemonitored and shared with the networked pumps 16, 28, 20. Actions of thepumps are not individualized, but instead they react as a system.

FIG. 7 is a flow diagram illustrating a non-limiting exemplary methodfor monitoring seawater temperature and preventing salt crystallizationin the seawater cooling loop 12 of the system 10 is shown.

At step 700, an operator may enter an alarm temperature at thecontroller 28, VFD 22, or other user interface. The alarm temperaturemay be a temperature at which salt may crystalize in the seawatercooling loop 12 and may resultantly clog the system 10.

At step 710, the system 10 may monitor a temperature of the seawater inthe seawater cooling loop 12. For example, the main controller 28 mayreceive a temperature measurement from the RTD 119. If it is determinedthat the measured seawater temperature exceeds some predeterminedthreshold temperature that is below the alarm temperature (e.g., 5degrees Celsius below the alarm temperature) but does not exceed thatalarm temperature, the system 10 may, at step 720, issue a warning tonotify the system operator(s) of such condition, and may further commandany active pumps 16-20 to operate at their maximum rated speed,regardless of the cooling demands of the engine 11, in order to lowerthe temperature of the seawater in the seawater cooling loop 12 andthereby prevent or mitigate salt crystallization and clogging.Additionally, if it is determined that the measured seawater temperatureexceeds the alarm temperature, the system 10 may, at step 730, issue analarm to the system operator(s), at which point more drastic measuresmay be taken to prevent, mitigate, and or remedy salt crystallizationand clogging within the system 10.

It will be appreciated that, as a result of operating the active pumps16-20 at their rated speed in order to cool the seawater to atemperature that prevents or mitigates salt crystallization, the freshwater in the fresh water cooling loop 14 may be cooled to temperaturesthat are below what is necessary for maintaining the engine 11 at adesired, safe operating temperature. In such a case, the main controller28 may additionally command the 3-way valve 102 to adjust its positionto divert some or all of the fresh water in the fresh water cooling loop14 to bypass the heat exchanger 15 in order to further reduce thecooling of the fresh water.

After the temperature of the seawater in the seawater cooling loop 12drops below the threshold temperature, the system 10 may, at step 740,return to normal operation, wherein the pumps 16-20 are driven partly orentirely in response to the cooling demands of the engine 11 in themanner previously described. The exemplary method set forth in FIG. 7thus facilitates automatic mitigation or prevention of saltcrystallization and resultant clogging within the system 10 using only asingle temperature input in the seawater cooling loop 12.

Referring now to FIG. 8, a method will be described for mitigatingclogging of the heat exchanger 15 and related components. In generalthis is accomplished by identifying an initial system resistance of thecooling system. For example, after a new installation or after a majorsystem maintenance, an operator can initiate an initial set-up operationon the main controller 28. The main controller 28 may then broadcastthis command to the controllers 30 and 32 over the communication link46. All of the pumps 16-20 in the network may then operate at apredefined speed (e.g., at their rated speeds), for a predefined amountof time. The system pressure will then be recorded into the controllers28, 30, and 32.

Thereafter, a clogging resistance (“clogging level”) of the coolingsystem can be periodically monitored, either through the use of a userconfigurable time schedule, or by on-demand manual operation. Duringsuch monitoring, all of the pumps in the network may be operated at thesame speeds as they were during the initial set-up operation (describedabove) for a predefined amount of time, and the system pressure may berecorded into the controllers 28, 30 and 32. The recorded systempressure may then be compared with the initial system resistance levelrecorded during the initial set-up operation. A warning/alarm canactivate if the system pressure exceeds the cooler cloggingwarning/alarm levels, to thereby remind the user to clean the coolingsystem using an automatic back flushing process, or by on-demand manualback flushing.

It is contemplated that a measured initial clogging level may bemanually modified by an operator within a certain amount of time afterthe above-described set-up operation, such as may be desirable forvarious reasons. For example, it may be desirable to manually modify theclogging level if the conditions of various valves in the system changeover time, or if certain loads in the system were not present or werenot considered during the initial set-up operation.

In some embodiments, when the current system clogging level reaches orexceeds the warning or alarm clogging level, the system canautomatically begin a predetermined back flushing operation byopening/closing the appropriate valves to direct flow through the heatexchangers 15 in a reverse direction (as compared to normal operationalcooling flow) to flush the system. This back flushing operation can, insome embodiments, be performed for a predetermined amount of time.Alternatively, it can be performed by a manually selected amount oftime.

After the back flushing operation is completed, the clogging supervisionoperation can be performed again to confirm that the current clogginglevel of the system is at a desired level below the warning/alarmlevels. If the current clogging level is not reduced by a sufficientamount after the first trial of back flushing, one or several more backflushing operations can be performed to reduce the current clogginglevel to a desired value. This function can be performed manually orautomatically. After several trials of back flushing operations, if thecurrent logging level is still higher than a desired value, a finalalarm can be activated to alert the user that cleaning of the coolingsystem is required.

The disclosed arrangement provides fully automatic supervision of theclogging level of the cooling system. With the integration of backflushing operation, cooling system cleaning maintenance can be reducedto a minimum (i.e., to when the cooling system really needs the user'sattention. This is a benefit compared to prior systems in which backflushing operations are automatically performed on a periodic basisand/or when the vessel is in port, which can result in eitherunnecessary cleaning or in undesirably delayed cleaning.

FIG. 8 is a flow diagram illustrating an exemplary method for monitoringa cooler clogging level of the system 10 is shown. The method may beemployed to determine the degree to which the seawater cooling loop 12of the system 10 has become clogged (e.g., by salt, debris, biologicalorganisms, etc.) relative to a normal operating level. The measuredlevel of clogging may then be used to determine whether manual and/orautomated steps should be taken to mitigate or remedy the clogging.

At step 800, an initial resistance level, or “initial clogging level,”of the system 10 may be determined, such as by running all of the pumps16-20 in the system 10 at their rated speed and measuring the systempressure in the seawater cooling loop 12 with the system pressuresensor. This measurement may be performed as part of an initial setup ofthe system 10, such as when the system 10 is installed or shortlythereafter. At step 810 the measured initial clogging level may bestored in memory, such as by the main controller 28, secondary control30, and backup controller 32. The initial clogging level may provide arelative baseline against which future measurements of the clogginglevel of the system 10 may be compared.

At step 820 the main controller 28 may use the initial clogging level todetermine a maximum clogging level. The maximum clogging level maysimply be a pressure value that is greater than the pressure value ofthe initial clogging level by some predetermined amount. Alternatively,it is completed that an operator may manually enter a maximum clogginglevel. In either case, the maximum clogging level may be stored inmemory.

At step 830 a clogging level test may be performed to determine acontemporaneous clogging level of the system 10 at some time after theinitial clogging level of the system 10 was measured. The clogging leveltest may include running all of the pumps 16-20 in the system 10 attheir rated speed and measuring a fluid pressure in the seawater coolingloop 12 in substantially that same manner as when the initial clogginglevel was determined. The clogging level test may be performedautomatically, such as accordingly to a predefined schedule (e.g., everyweek, every month, etc.). Alternatively, the clogging level test may beinitiated manually at the discretion of an operator, such as through theentry of an appropriate command at an operator interface.

At step 840 the contemporaneous clogging level may be compared to themaximum clogging level, such as by the main controller 28. If it isdetermined that the contemporaneous clogging level exceeds the maximumclogging level, the system 10 may, at step 850, issue a warning tonotify the system operator(s) of such condition and may furtherautomatically initiate a back flushing operation (described above),whereby the flow regulation valves 115,116 of the seawater cooling loop12 may be closed and the flow regulation valves 117,118 may be opened toreverse the flow of seawater through the heat exchanger 15. The backflushing may reduce or eliminate the clogging in the system 10.

After the back flushing operation the system 10 may, at step 860 repeatthe clogging level test to determine a new contemporaneous clogginglevel. At step 870, the new contemporaneous clogging level may becompared to the maximum clogging level. If it is determined that thecontemporaneous clogging level still exceeds the maximum clogging level,the system 10 may, at step 880, repeat the back flushing procedure. Thiscycle of testing and back flushing may be repeated a predeterminednumber of times, and if the contemporaneous clogging level still exceedsthe maximum clogging level the system may, at step 890, issue an alarmto the operator(s) of the system 10 indicating that the system 10 shouldbe manually cleaned or that other measures should be taken to reduce theclogging.

As will be appreciated, the exemplary method facilitates automaticmonitoring and mitigation of clogging in the system 10, thereby reducingthe amount of manual monitoring and intervention that is necessary tooperate and maintain the system 10.

Referring now to FIG. 9, a method will be described for adjustable pumpswitching overlapping operation of the pumps 16, 18, 20 will bedescribed. When the system switches from one pump to another (eitherduring scheduled switchover, alarms, or cascading), pressure mayfluctuate, mostly reduced, due to a time gap between the switching. Thiscan cause the related pumps cease operation momentarily, eventuallytriggering a system pressure low alarm.

To minimize or eliminate such alarm, during the operation, if one of theoperating pumps 16, 28, 20 must be shut down (e.g., due to varioussystem normal operations, or shut-down alarms), that pump will send outa request to the backup pump. When the backup pump receives the requestto join into the system operation, the backup pump will start running.At same time, if the backup pump starts running successfully, the backuppump will send an acknowledgement “ack” back to the originator pump.Once the originator pump receives the “ack” from the backup pump, theoriginator pump can prepare to shut itself down.

This manner in which the originator pump disconnects itself fromoperation can be a user configurable time delay, or it can be acontrolled ramp-down along with a controlled ramp-up of the backup pump,to provide maximum stability of system pressure, and/or to maintainstability of flow.

In some embodiments, if the originator pump does not receive an “ack”from the backup pump (e.g., due to the loss of communication on thecommunications link 46), the originator pump may continue to operate ifit is not under critical shut-down alarms. If the communications link 46is in good condition, the originator controller will get an “ack” fromthe backup controller, either indicating it has successfully joined theoperation, or that it cannot join the operation due to its own shut-downsituations. Under either circumstance, the originator pump willshut-down accordingly.

The disclosed arrangement enables the originating pump and the backuppump to handshake with each other to coordinate the pump switchingoperation, to ensure the proper operation of the cooling pumps and toensure proper flow is maintained within the system. Pump switchingoperations can be configured for optimizing pressure stability or flowstability without any gap during switching. Information can be sharedwithin the networked pumps, and pump actions are not individual, butreact as a whole system;

Referring to FIG. 9, a flow diagram illustrating an exemplary method foroverlapping the operation of the pumps 16-20 in the system 10 is shown.The method may be employed to prevent fluctuations in system pressurethat might otherwise result from abrupt pump shutdown and startup whenone pump takes over operation for another, such as may occur as a resultof pump malfunction or scheduled pump switchover as described above.

At step 900, a first of the pumps 16-20 that is to be shut down willsend a request to a second of the pumps 16-20 that is to take overoperation for the first pump. If the communication link 46 is in goodcondition and the second pump is able to receive the request andsuccessfully start up, the second pump may, at step 910, send anacknowledgement back to the first pump. Subsequently, if thecommunication link 46 is still in good working condition and the firstpump receives the acknowledgment from the second pump, the first pumpmay, at step 920, prepare to shut down. However, if the communicationlink 46 is not in good working condition and the first pump does notreceive an acknowledgment from the second pump in a predetermined amountof time, the first pump may, at step 930, continue to operate normallywithout shutting down if it is not under critical shut-down alarms.

The above-described “hand-off” operation from the first pump to thesecond pump may be performed in a simple, timed manner, wherein thefirst pump continues to operate at its then-current speed for apredetermined amount of time after receiving an acknowledgement from thesecond pump. Alternatively, the hand-off may be performed in a graduatedmanner, wherein the speed of the first pump is reduced or ramped downwhile the speed of the second pump simultaneously increased or ramped upat a substantially identical rate. The latter hand-off method mayachieve a more stable system pressure during the transition from thefirst pump to the second pump.

The exemplary method set forth in FIG. 9 thus facilitates smooth andautomatic transitions between the pumps 16-20 in the system 10 in amanner that prevents, or at least mitigates, abrupt lapses in systempressure that could otherwise cause system operation disruptions.

As used herein, the term “computer” may include any processor-based ormicroprocessor-based system including systems using microcontrollers,reduced instruction set circuits (RISCs), application specificintegrated circuits (ASICs), logic circuits, and any other circuit orprocessor capable of executing the functions described herein. The aboveexamples are exemplary only, and are thus not intended to limit in anyway the definition and/or meaning of the term “computer.”

The computer system executes a set of instructions that are stored inone or more storage elements, in order to process input data. Thestorage elements may also store data or other information as desired orneeded. The storage element may be in the form of an information sourceor a physical memory element within the processing machine.

The set of instructions may include various commands that instruct thecomputer as a processing machine to perform specific operations such asthe methods and processes of the various embodiments of the invention.The set of instructions may be in the form of a software program. Thesoftware may be in various forms such as system software or applicationsoftware. Further, the software may be in the form of a collection ofseparate programs, a program module within a larger program or a portionof a program module. The software also may include modular programmingin the form of object-oriented programming. The processing of input databy the processing machine may be in response to user commands, or inresponse to results of previous processing, or in response to a requestmade by another processing machine.

As used herein, the term “software” includes any computer program storedin memory for execution by a computer, such memory including RAM memory,ROM memory, EPROM memory, EEPROM memory, and non-volatile RAM (NVRAM)memory. The above memory types are exemplary only, and are thus notlimiting as to the types of memory usable for storage of a computerprogram.

1. A seawater cooling system for monitoring and reducing clogging in aseawater cooling loop, the system comprising: a pressure sensoroperatively connected to the cooling loop and configured to measure afluid pressure of seawater in the cooling loop; a plurality of valvesoperatively connected to the cooling loop and configured to selectivelychange a flow direction of the seawater through the cooling loop betweena first direction, during normal operation, and second directionopposite the first direction, during a back flushing operation; and acontroller operatively connected to the pressure sensor and to theplurality of valves, the controller configured to operate the pluralityof valves to change flow from the first direction to the seconddirection when the pressure of the seawater exceeds a pressure levelassociated with a predetermined maximum clogging level.
 2. The seawatercooling system of claim 1, wherein the controller is configured tooperate the plurality of valves based on a manual user input.
 3. Theseawater cooling system of claim 1, wherein the controller is configuredto maintain the flow direction of the seawater through the cooling loopin the second direction for a predetermined period of time.
 4. Theseawater cooling system of claim 3, wherein the controller is configuredto adjust the positions of the plurality of valves after thepredetermined period of time has elapsed so that the flow direction ofthe seawater through the cooling loop is configured in the firstdirection.
 5. The seawater cooling system of claim 1, wherein pressurelevel associated with the predetermined maximum clogging level is apredetermined value higher than an initial system resistance pressurelevel.
 6. A method for monitoring and reducing clogging in a seawatercooling loop, the method comprising: circulating seawater through thecooling loop using a pump operating at a predetermined speed; measuringa pressure of the seawater while the pump is operated at thepredetermined speed; comparing the measured pressure to a predeterminedpressure, the predetermined pressure associated with a baselinecondition of the cooling loop; and reversing the circulation directionof the seawater through the cooling loop when the measured pressureexceeds the predetermined pressure by a predetermined amount.
 7. Themethod of claim 6, wherein the baseline condition is a condition of thecooling loop at new installation or after system maintenance.
 8. Themethod of claim 6, wherein the circulation direction of the seawater isreversed for a predetermined amount of time.
 9. The method of claim 8,wherein after the predetermined amount of time has elapsed, thecirculation direction of the seawater is returned to an original flowdirection.
 10. The method of claim 6, wherein the circulation directionof the seawater is reversed automatically, without user intervention.11. An overlapping pump system, comprising: first and second pumpscoupled to a seawater cooling loop for circulating seawater through theseawater cooling loop; and first and second controllers operativelycoupled to the first and second pumps, respectively; and the first andsecond controllers configured to perform a handshake operation forswitching operation between the first and second pumps, the handshakeoperation comprising: sending, from the first controller to the secondcontroller, a request for the second controller to start operation ofthe second pump, upon receipt of the request, sending, from the secondcontroller, an acknowledgement to the first controller when the secondpump is capable of starting operation, and upon receiving, at the firstcontroller, the acknowledgement, the first controller shutting down thefirst pump.
 12. The system of claim 11, the handshake operation furthercomprising; maintaining operation of the first pump if the firstcontroller does not receive the acknowledgement from the secondcontroller within a predetermined period of time after sending therequest.
 13. The system of claim 11, wherein the handshake operationincludes the first controller operating the first pump at a currentspeed for a predetermined period of time after receiving theacknowledgement form the second controller.
 14. The system of claim 11,wherein the handshake operation includes the first controller reducing aspeed of the first pump after receiving the acknowledgement from thesecond controller and the second controller increasing a speed of thesecond pump after sending the acknowledgement.
 15. A method foroverlapping operation of a first pump and a second pump, the methodcomprising: sending, from a first controller coupled to the first pump,a request to a second controller coupled to the second pump, a requestfor the second controller to start operation of the second pump; uponreceipt of the request, sending, from the second controller, anacknowledgement to the first controller when the second pump is capableof starting operation; and upon receiving, at the first controller, theacknowledgement, shutting down the first pump.
 16. The method of claim15, further comprising maintaining operation of the first pump if thefirst controller does not receive the acknowledgement from the secondcontroller within a predetermined period of time after sending therequest.
 17. The system of claim 15, wherein the first controlleroperates the first pump at a current speed for a predetermined period oftime after receiving the acknowledgement form the second controller. 18.The system of claim 15, wherein the first controller reduces a speed ofthe first pump after receiving the acknowledgement from the secondcontroller and the second controller increases a speed of the secondpump after sending the acknowledgement.